Linux 'ENOSPC: System limit for number of file watchers reached' (Node/webpack/Vite/Jest watch mode) or VS Code 'unable to watch for file changes in this large workspace'. How do I fix it?

Cause: file watchers on Linux use inotify, and the kernel limits how many watches each user can create (fs.inotify.max_user_watches). Large projects (node_modules, virtual environments, build outputs, monorepos) and several watching tools at once (editor, dev server, test runner) can exhaust the limit. The error says ENOSPC (no space), but it has nothing to do with disk space. Fix: 1. Watch less first: exclude big folders. In VS Code add them to files.watcherExclude (e.g. **/.venv/**, **/node_modules/*/**, build and dist folders); in webpack/Vite/Jest configure their watch ignore options for node_modules and output folders. Close other watching tools you don't need. 2. Check the current limit: cat /proc/sys/fs/inotify/max_user_watches. 3. Raise it persistently: add fs.inotify.max_user_watches=524288 to /etc/sysctl.conf, or to a file under /etc/sysctl.d/ (VS Code's docs note newer Ubuntu and Arch use the sysctl.d directory), then load it with sudo sysctl --system. 4. Mind memory: each watch uses roughly a kilobyte of kernel memory, so the maximum value above can use several hundred MiB if fully used; pick a lower value on small machines. 5. In containers, the limit comes from the host kernel; raise it on the host (or the Docker Desktop VM), not inside the container. 6. If you also see 'too many open files', that's a different limit (ulimit -n / fs.inotify.max_user_instances). Verify: cat /proc/sys/fs/inotify/max_user_watches shows the new value after a reboot, and the watcher starts without ENOSPC. Sources: https://code.visualstudio.com/docs/setup/linux https://man7.org/linux/man-pages/man7/inotify.7.html